The Internet is global collection of people's computers, which are linked together by cables and telephone lines making communication possible among them in a common language. However, the rigid technological definition of Internet is that it is a global collection of interconnected networks. By definition, a network allows computer users to share computer equipment and programs, messages, and the information available at one site.
How does Internet Work?
A computer network by definition allows sharing of resources. Since all softwareresources exist in computers in the form of files of data, one of the key aspect in network of many computers is to move data between two specific computers. For such a communication, we require:
* The address of the destination.
* a safe means of moving data in the form of electronic signals.
As far as safe movement of data is concerned, there exists a set of rules, which govern the sending and receiving of data on the Internet. These rules are implemented in two parts in the networks software and are called Transmission Control Protocol (TCP) and Internet Protocol (IP). These two are collectively called TCP/IP. For sending a large block of text/data to another machine, TCP divides the data into little data packets. It also adds special information, e.g. the packet position, error correction code etc., to make sure that packets at the destination can be reassembled correctly and without any damage to data. The role of IP here is to put destination-addressing information on such packets.
The following can be a typical person-understandable address on Internet: user firstname.lastname@example.org
The user name in general is the name of the Internet account. This name is same as the one, which you may use when logging into the computer on which you have your Internet account (Logging in is the process of gaining access to your account on a computer, which is shared by several users). Your Internet account is created on it.
Hosts are in general, individual machines at a particular location. Resources of a host machine is normally shared and can be utilised by any user on Internet.
Domains are general category that a computer on the Internet belongs to. The most common high level domains are .com, .org etc.
Tools & Services on Internet
To work with Internet and to utilise some of the points mentioned above we use certain tools. For example, Telnet is a tool, which is utilised for logging on remote computers on the Internet.
One of the very useful things about the Internet is that it allows you almost instant
exchange of electronic message (e-mail) across the world. E-mail is mainly used for sending electronic piece of text.
USENET and News Groups
On Internet there exists another way to meet people and share information. Onesuch way is through USENET newsgroups. These are special groups set up by people who want to share common interests ranging from current topics to cultural heritages.
The newsgroups are really meant for interaction of people who share your interests.
You can post your own questions as well as your answers to the questions of others, on the USENET.
Frequently Asked Questions (FAQ)
Agreat resource offered by USENET is the FAQs, that is the list of frequently asked questions and responses for them for particular newsgroup. FAQs are an excellentsharing place for learning about a topic.
These FAQs are generally text files or USENET articles.
Connecting to Remote Machine with Telnet
Telnet is a program that allows an Internet host computer to become a terminal of another host on the Internet. Telnet allows to become a user on a remote machine. You can run the Internet computer programs available on that machine.
Gopher displays a set of resources on the Internet in the form of menus or lists of items. You go around the Internet by selecting items from these menus. You need not know the addresses and commands. You just select an item of interest to see its content on the screen.
The Hyper Text Markup Language (HTML) is a language used for creating documents
for the World Wide Web. Although most browsers will display any document that is written in plain text, there are advantages to writing documents using HTML. When HTML documents are read by applications specifically designed for the WWW, they can include formatting, graphics and even links to other documents and websites on the World Wide Web.
Standard Generalised Markup Language (SGML) is used for defining the structure and managing the contents of any digital document. HTML used in many world wide web document on the Internet is a part of SGML.
World Wide Web
It is a huge collection of hyper text pages on the Internet. It is one of the most flexible and exciting tools in existence for surfing the Internet.
Hyper text link connects the pieces of information (text, graphics, audio or video) in separate HTML pages created at the same or at different Internet sites.
Hyper Text Transport Protocol (HTTP) is used to manage the links between one hyper text document and another.
HTTP is the mechanism that opens the related document when you click on a hyper text link, no matter where on the Internet that related document happens to be.
It is an initial starting page. A home page on the Internet may be related to a single person, a specific subject, or to a corporation, and is a convenient jumping-off point
to other pages or resources.
Uniform Resource Locater (URL) is a method of accessing Internet resources. URLs contain information about both the access method to use and also about the resource itself, and are used by web browsers to connect you directly to a specific document or page on the World Wide Web, without you having to know where that resources is located physically.
A search service built into the Gopher Internet application. When you use Veronica to search a series of Gophermenus (files, directories, and other items), the results of the search are presented as another Gopher menu, which you can use to access the resources your search has located. Veronica supposedly stands for Very Easy Rodentoriented Net-wide Index to computer Archives.
Abbreviation for Wide Area Information Service, pronounced "ways". A service used to access text databases or libraries on the Internet.
WAIS uses simple natural-language queries, and takes advantage of index searches for fast retrieval. Unlike Gopher, which only searches through the names of Gopher resources, WAIS can search the content of all documents retrievable from WAIS databases. WAIS is particularly adept at searching through collections of articles, USENET newsgroups, electronic texts and newspaper archives.
Browser: An application programme used to explore Internet resources.
A browser lets you wander from node to node without concern for the technical details of the links between the nodes or the specific methods used to access them, and presents the information- text, graphics, sound, or video - as a document on the screen.
Web browser: A World Wide Web client application that lets you look at hyper text documents and follow links to other HTML documents on the Web. When you find something that interests you as you browse through a hyper text document, you can click your mouse on that object, and the browser automatically takes care of accessing the Internet host that holds the document you requested; you don't need to know the IP address, the name of the host system, or any other details.
Mosaic: It is a World Wide Web client program. Mosaic uses a graphical user interface to give access to Internet resources, and allows users to navigate through hyper text documents quickly and easily using a mouse.
FTP: Abbreviation for the File Transfer Protocol. The protocol used to access a remote Internet host, and then transfer files between that host and your own computer. FTP is also the name of the program used to manage this protocol. FTP is based on client/ server architecture;
you run an FTP client program on your system, and connect with an FTP server running on the Internet host computer.
Archie: A system used on the Internet to locate files available by anonymous FTP. Once a week, special programs connect to all the known anonymous FTP sites on the Internet and collect a complete listing of all the publicly available files. This listing is kept in an Internet archive database, and when you ask archie to look for a file, only this database is searched rather than the whole Internet; you can then use anonymous FTP to retrieve the file.
Modem: Contraction of modulator/ demodulator; a device that allows a computer to transmit information over a telephone line. The modem translates between the digital signals that the computer uses, and analog signals suitable for transmission over telephone
lines. When transmitting, the modem modulates the digital data onto a carrier signal on the telephone line. When receiving, the modem performs the reverse process, and demodulates the data from the carrier signal.
Internal modem: A modem that plugs into the expansion bus of a personal computer.
External modem: A stand-alone modem, separated from the computer and connected by a serial cable.
LEDs on the front of the chassis indicate the current modem status, and can be useful in troubleshooting communications problems.
X-modem: In communication, a popular file transfer protocol available in many off the- shelf and shareware communications packages, as well as on many bulletin boards.
X-modem divides the data for the transmission to blocks; each block consists of the start-of-header character, a block number; 128 bytes is returned to the sender if the check sum calculation is identical to the sender's check sum; however, this requirement to acknowledge every block can cause poor performance.
An extension to X-modem, called X-modem-CRC, adds a more stringent errorchecking method by using a cyclical redundancy check to detect transmission errors rather than X-modem's simple additive check sum.
Y-modem: Y-modem, a variation of the X-modem protocol, divides the data for thetransmission into blocks; each block consists of the start-of-header character, a block number, 1K of data, and a check sum. Y-modem's larger data lock means less overhead for error control when compared with X-modem, but if the block has to be retransmitted because the protocol detects an error, there is more data to resend.
Y-modem also incorporates the ability to send multiple files in the same session, and to abort file transfer during the transmission.
Z-modem: Z-modem is similar to X-modem and Y-modem but is designed to handle larger data transfer with fewer errors, Z-modem also includes a feature called checkpoint restart that allows an interrupted transmission to resume at the point of interruption, rather than starting again at the beginning of the transmission. If you have a choice between several protocols, choose Z-modem if you can; it is fast as well as convenient.
Newbie: A newcomer coming to Internet world is known as a newbie.
Netiquette: A contraction of network etiquette. The set of unwritten rules governing the use of e-mail, USENET news groups, and other online services.
Contraction of USEr NETwork an international, non commercial network, linking many thousands of Unix sites.
Although there is a very close relationship between the Internet and USENET, they are not the same thing by any means.
USENET predates the Internet; in the early days, information was distributed by dial - up connections. Not every Internet computer is part of USENET, and not every USENET system can be reached from the Internet.
Like the Internet, USENET has no central governing body; USENET is run by the people who use it.
On the Internet, a USENET newsgroup of mailing list which is managed by one or more people in an attempt to maintain standards for the newsgroup. All posts to the newsgroup are reviewed by the moderator to make sure that they meet the standards the newsgroup has set for subject and commercial content before being passed on to the whole group. Moderation is not censorship, but an attempt to avoid some of the more extreme antics of those who enjoy flaming and flame wars.
A person or small committee of people who review the contents of all posts to a USENET newsgroup or mailing list in an attempt to ensure that the postings meet the standards set by the group.
Moderators are almost always volunteers.
A USENET newsgroup or mailing list in which posts are not subject to review before distribution. You will find the discussions in unmoderated newsgroups to be wildly spontaneous, but they will also contain more than their fair share of flames and flame wars.
A deliberately insulting e-mail message or post to a USENET newsgroup, usually containing a personal attack on the writer of an earlier post. Flames are often generated by established newsgroup members when a newbie posts a question which is answered in the newsgroup's FAQ.
An insulting or outrageous posting to a USENET newsgroup specifically designed to provoke other subscribers into flaming the originator.
A prolonged series of flames in a USENET newsgroup which may have begun as a creative exchange of views but which quickly degenerates into personal attacks and crude name - calling.
An individual article or e-mail message sent to a USENET newsgroup or to a mailing list, rather than to a specific individual. Post can also refer to the process of sending the article to the newsgroup.
In a USENET newsgroup, a public message posted via an anonymous server in order to conceal the identity of the original author. This server removes all the information from the message that could identify the sender, and forwards the message to its destination. If you ever use an anonymous server, don't forget to remove your signature from the bottom of your posting.
Abbreviation for Multipurpose Internet Mail Extensions. A set of extensions that allows Internet e-mail users to add non - ASCII elements such as graphics, post script files, audio or video to their e-mail. Most of the common e-mail client programs include mime capabilities.
Amethod of accessing an internet computer with the FTP (file - transfer program) which does not require that you have an account on the target computer system. Just login to the Internet computer with the uఅser name anonymous and use your e-mail.